The present invention relates to an antenna board, and particularly to a method for fabricating an electromagnetic induction digitizer antenna board adapted for handwriting input.
Currently, electromagnetic induction antennas for handwriting input are usually fabricated by the printing technology, in which multiple layers of printed circuits are stacked one on another to achieve induction positioning of a plurality of electromagnetic induction coils. Regarding the antenna fabricating technology for large-size electromagnetic induction digitizer, people skilled in the art tried to realize the automatic coiling of metal wires by simulating the manual coiling method. However, doing this requires large investment in equipment development, and particularly it is very difficult to realize, and the equipment are often complicate for operation, not reliable, and hard for maintenance. Therefore, this approach may hardly save cost, and so far the technology is far from workable. China Patent number CN102447162B discloses an invention, in which ultrasonic embedding technology is introduced to implant the coil inside the surface of the substrate, e.g., PVC substrate, so as to fabricate a large-size antenna board with a lower cost. However, one of the biggest difficulties of such technology is that there are too many intersection points between coils. Therefore, during the ultrasonic embedding process, according to this technology, intersection points are often skipped. As such, when there are many intersection points, the process will be very slow, and the working efficiency will also be low. In addition, it also leads to additional machine depreciation, as well as other problems such as wire breaking. China Patent Application Number CN102760939A modifies the ultrasonic embedding technology, in which, for the purpose of reducing the intersection points, non-overlapping coils are disposed in the same layer and prepare a plurality of layers, and then all the layers are compressed into an antenna board. Unfortunately, such an approach makes the antenna board much thicker, and also introduces additional difficulty to the fabrication. In summary, the conventional technologies for fabricating antenna boards of electromagnetic induction digitizers mainly have the following defects: regarding the conventional thin film type and printing circuit board type antennas, the cost is very high and it's very difficult to fabricate large-size antennas; regarding the manual coiling method, the working efficiency is low, and it requires a lots of manpower, and further the product quality is often inconsistent, thus the production yield will be low; regarding the complex automatic coiling machine, the equipment is usually very expensive, and complicate to maintain, while the technology is still under-development, and thus difficult to extensively use; as to the ultrasonic embedding equipment which is relatively well used, the technology is still too complicate, the working efficiency is still low, and the antenna board is thick.